64 ELEMENTARY BIOLOGY. [CHAP. 



and downwards, into a stout rod or suspensorium, 

 which lies between the pterygoid and squa- 

 mosal and furnishes the articulation for the 

 lower jaw. 



The olfactory capsules ; confluent with each other 

 and the cranium, and incompletely separated 

 above by a median longitudinal furrow. The 

 dorsal wall of each will be seen to be scroll- 

 shaped and produced — in front, into a blunted 

 pre-nasal process, which abuts against the inner 

 face of the maxilla (cf. opposite side) ; behind, 

 into a laminate ali-nasal process, which encircles 

 the outer and hinder margins of the anterior 

 nostril. 



If the preparation be made with great care, the 

 front wall of the narial passage will be seen to 

 lodge a couple of minute labial cartilages, which 

 overlie the base of the pre-nasal process. 



b. Ventral aspect. 



a. The cranium; completely cartilaginous below 

 and at the sides. Note the limits of the car- 

 tilage bones. 



Certain apertures (exits for cranial nerves) 

 will be seen ; they are best studied later. 



/?. The sub-ocular arch; in front, confluent with 

 the expanded floor of the olfactory capsule; 

 behind, in articulation with the ventral outer 

 border of the auditory capsule. 



y. The rhinal processes. That of the dissected side 

 will be seen as a small hammer-shaped cartilage 

 lying near the middle-line in front, ventral to 



